Cyperus congestus
Vahl Dense Flat-sedgeTufted perennial with very short thick rhizome, often apparently annual. Culms triquetrous, smooth, slightly swollen at base, mostly 20–60 cm high, 1–3 mm diam. Leaves not septate-nodulose, shorter or longer than culms, 2–6 mm wide. Inflorescence simple or compound with 2–7 branches to 10 cm long, or head-like; spikes dense, broad-cylindric to hemispherical, 1–5 cm diam.; involucral bracts leaf-like, 2 or 3 longer than inflorescence. Spikelets flattened, numerous per spike, 10–28 mm long, 1–2 mm wide in side view, 8–24-flowered; rachilla winged, persistent; glumes acute, with sides 3–4-nerved, red-brown, c. 4 mm long; stamens 3; style 3-fid. Nut trigonous, narrow-obovoid, dark brown to black, c. one half as long as glume, c. 1.5 mm long, c. 0.6 mm diam. Flowers spring–summer.
VVP, VRiv, GipP, OtP, Gold, CVU, EGL, EGU, HSF, HNF, Strz. Also WA, SA, NSW, ACT, Tas. Native to southern Africa. Weed by roadsides and in damp ground.
Wilson, K.L. (1994). Cyperaceae. In: Walsh, N.G.; Entwisle, T.J., Flora of Victoria Vol. 2, Ferns and Allied Plants, Conifers and Monocotyledons, pp. 238–356. Inkata Press, Melbourne.